Nuclear wastes containing large amounts of boric acid are generated during the operation of pressurized water reactor (PWR) electrical generating plants. Other sources of such wastes are low level burial sites which have either intercepted and stored run-off from the burial trenches or received unacceptable, unsolidified boric acid waste.
The most popular method for solidifying low level waste in power plants is to concentrate the waste to 12% boric acid in waste evaporators, then mix the waste with concrete. Alternatively, a bitumen or a water expandable polymer may be mixed with the waste to produce a solid mass. While methods for reducing the volume of the waste have been devised, the volume of the waste is still large, and the high concentrations of boric acid in the waste may interfere with the setting of concrete. Also, boric acid is a very leachable substance in concrete and as it leaches out, it leaves pores through which the radionuclides can escape.